Carburetor accelerating pump



NW0 M 319% Q. HENNHNG CURETOR ACCELERATING PUMP Filed Dec. 17, 1945 INVENTOR. TTO HENNENG ATTORNEY Patented Nov. 14, 1950 it 2,529,855 CARBURETOR ACCELERATING PUMP Otto Kenning, Clayton, Mo., assignor to Carter Carburetor Corporation, St. Louis, Mo., a corporation of Delaware Application December 17, 1945, Serial No. 635,572

I 4 Claims.

This invention relates to carburetors for internal combustion engines and consists particularly in a novelaccelerating pump device therefor.

Carburetors for automotive engines are cus- 2 ment, indicated at ll, controlled by a metering rod I 2 which. is operated by a diaphragm contained in a housing I 3. Detail construction of this metering rod control is illustrated in applitomarily supplied with accelerating pumps which 5 cation Serial No. 333,759, filed May 7, 1940, now inject an extra charge of fuel into the engine Patent No. 2,328,604 issued Sept. 7, 1943 in the intake manifold as the throttle valve is opened name of George M. Bicknell and assigned to the or as the intake manifold suction drops. The assignee of the present invention. Idling fuel purpose of the pump is to insure the supply of an is supplied through passages M and I! to a port adequate fuel charge to the engine cylinders dur- I3 located adjacent the edge of the throttle valve ing the interval when the discharge from the when closed. main nozzle becomes inadequate to form the Attached to the carburetor body opposite diaproper mixture with the increased air component phragm housing I3 is a second diaphragm housdue to the inertia of the liquid fuel. It would be ing it which secures in position a diaphragm l9. desirable for the pump to supply a substantial A hollowed space on the inside of this diainitial charge and a reduced charge for an exphragm forms the accelerating pump pressure tended period until the main nozzle fuel flow chamber which communicates with the constant reaches its normal rate. However, accelerating level chamber through passages 2|, 22, and 23. pumps as at present constructed provide a uni- Passage 22 receives an inlet check valve 24. Fuel form charge throughout the movement of the 20 is discharged into the mixture conduit through pumping member. The difficulty is aggravated an outlet passage 23 and restricted nozzle 26. where the pumping is produced by a spring and Passage 25 receives'an'outlet check valve 21. suction operated diaphragm because of the tend- Diaphragm I! has a central orifice in which ency thereof to make a full stroke rapidly duris secured a cylinder surrounded by a coiled ing each operation. compression spring 3 I. The space between cylin- The main object of the present invention is to der so and easing I8 is connected by a passage 32 provide a carburetor accelerating pump which can to a port 33 located in the outlet of the carburetor be adjusted to supply the proper discharge both mixture conduit posterior to the throttle valve. initially and during an extended period. 1 The arrangement is such that the suction trans- I A more detailed object is to provide an accel- 30 mitted through port 33 and passage 32 tends to crating pump which will have a strong initial draw diaphragm Is to the left against coiled discharge and thereafter a reduced discharge for spring 3| so as to draw a charge of fuel past check an extended period. I 24 into the pressure chamber. When the suc- These objects and other more detailed objects tion drops, as occurs when the throttle valve is hereafter appearing are attained by the device 35 op d r w h sp d f he en in is reillustrated in the accompanying drawing in which duced, spring 3| moves diaphragm l 9 to the right Fig. 1 is a side view, partly sectioned, illusto force a charge of liquid fuel past check 21 trating an automotive carburetor embodying the through nozzle 26 into the mixture conduit. invention. A boss-like structure 35 projects outwardly Fig. 2 is a detail section illustrating the accelfr m h carburetor b dy r h h aforemeus erating pump during the initial discharge. tioned central orifice in diaphragm i9 and is re- Fig. 3 is a section taken on line 3-3 of Fig. 1. ceived in cylinder 30. This structure forms a The carburetor in Fig. 1 comprises a downdraft stationary plunger which cooperates with cylinmixture conduit 5 having a series of Venturi tubes der 30 to form a dash pot. A passage 36 con- 3 into the smallest of which main nozzle 1 disnects the dash pot chamber, between structure charges. The entry of air to the upper end of 35 and the interior of cylinder 30, and pump inlet the conduit is controlled by abutterfly choke valve passage 22. A cup 31 secured to the end of the 8 and the discharge of mixture from the lower plunger structure has an annular shoulder 33 end thereof is controlled by a throttle valve 9. between which and the end of structure 35 is An arm l0 secured to one end of the throttle movably positioned a perforated check valve 33. shaft provides for manual operation of this valve. As best shown in Fig. 3, the check valve has an A supply of fuel is stored in the constant level outer series of perforations l0 and a central perbowl of the usual type formed on the rear side of foration 4|. During the inward movement of the carburetor. In the lower .part of this bowl cylinder 30 and diaphragm l9, valve 39 ismoved I there is provided .a main metering orifice ele- 6 to the right so as to seat against the end of plunger structure 35, closing outer perforations 59. Thereafter, liquid fuel on the interior of cylinder 30 is forced through single central hole 6| of the check valve and passages 36 and into the carburetor. This results in a restraining action upon the discharging movement of the diaphragm under the influence of spring 3|. However, the initial movement of the diaphragm from the fully charged position shown in Fig. 1, while this check is moving from collar 38 against the plunger structure, is substantially free of the restraining influence of the dash pot. During the charging movement the diaphragm and cylinder move leftwardly and disk check 39 is forced against collar 38 which forms its leftward seat. During this movement liquid is drawn into the interior of cylinder through all of the openings and 4| so that the charging stroke is substantially unrestrained.

Fig. 2 shows cylinder 3!] moved slightly to the right or in the discharging direction through about the distance necessary to transfer the disk check from its left hand seat on collar 38 to its right hand seat on plunger structure 35. Therefore, the indicated movement of cylinder 30 and diaphragm I9 is substantially free of the restraining infiuence of the dash pot and, consequently. a maximum pump discharge is supplied to the carburetor mixture conduit. The remainder of the discharge stroke is substantially slower because of the dash pot action so that a reduced accelerating discharge is supplied for an extended period.

The principles of the invention may be embodied in an accelerating pump having a movable piston instead of a diaphragm and the dash pot parts may be reversed if desired so that the plunger moves with the pump diaphragm or piston and the dash pot cylinder is stationary. The invention may be modified in these and other respects as will occur to those skilled in the art and the exclusive use of all modifications as come within the scope of the appended claims is contemplated.

I claim:

1. In a carburetor, a fuel supply chamber, a mixture conduit, and an accelerating pump comprising a pressure chamber, a diaphragm forming a movable wall therefor, said diaphragm having a central orifice, a cylinder secured in said orifice, a stationary plunger received in said cylinder and forming a dash pot therewith, fluid connections between said supply chamber and the pump pressure and dash pot chambers, a check valve in one of said dash pot connections, and opposing substantially spaced valve seats for said valve, said valve being apertured and one of said seats being constructed relative thereto so that the passage of fluid in said last connection is substantially unrestricted when said valve engages said last seat, the other valve seat being constructed and arranged to substantially rcstrict fluid flow in said last connection when said valve is seated thereagainst, and there being substantial clearance past said valve when free of both of said seats whe eby said diaphragm and cylinder are permitted initial movement in one direction substantially free of restriction from said dash pot and subsequent movement of said .6. diaphragm in said direction is restricted by said dash pot.

2. In a carburetor, a mixture conduit, 9. fuel supply chamber, and an accelerating pump comprising a pressure chamber having a movable wall, yielding means for urging said wall in the discharging direction, means to move said wall in the charging direction, and a dash pot device having a movable element operatively connected to said pump movable wall for effecting the movement thereof, a fluid connection for the dash pot chamber, an apertured check valve in said connection, and substantially spaced seats for said valve whereby initial movement of said pump wall during transfer of said check valve between said seats is effected substantially free of the restraining influence of said dash pct.

' 3. 'A carburetor accelerating pump comprising a pressure chamber having a movable wall and check valve controlled inlet and outlet ducts, a dash pot device operatively connected to said wall for effecting the movement thereof, a fluid connection for said dash pot, and an apertured check valve in said connection having stops spaced axially of the valve movement, said valve being urged against a first of said stops for constituting a maximum restriction during discharge movement of said movable wall and being urged against the other stop during charging movement of said wall for constituting a minimum restriction, said dash pot resisting movement of said pump wall when said check valve is against said first stop, said stops being substantially spaced so as to permit initial movement of said pump wall in the discharge direction free of said dash pot.

4. A carburetor accelerating pump comprising a pressure chamber having a movable wall, a separate dash pot device operatively connected to said wall for effecting the movement thereof, fluid inlet and outlet connections for said dash pot, and an apertured check valve in said outlet connection having spaced seats, said valve being urged against a first of said seats for constituting a maximum restriction during discharge movement of said movable wall and being urged against the other seat during charging movement of said wall for constituting a minimum restriction, said valve seats being spaced sufficiently so that said pump wall is permitted slight initial movement in the discharge direction substantially free of restriction by said dash pot device for causing a strong initial pump discharge and a weaker discharge thereafter.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,260,810 Richard Mar. 26, 1918 1,796,734 Tice Mar. 1'7, 1931 1,816,070 Berry July 28, 1931 1,934,240 Scott Nov. 7, 1933 2,048,727 Boyce July 28, 1936 2,109,260 Chandler et a1 Feb. 22, 1938 2,212,946 Mock et al Aug. 27. 1940 

